On the one hand, this invention relates to a harness device for a weaving machine comprising an apertured board provided with threading openings for pulling through a series of harness cords and a method for building up such a harness device on the other hand.
In a Jacquard weaving machine, the harness is the connection between the warp yarns of the weaving machine and the hooks and/or the tackle system of the Jacquard machine driving the different positions of the warp yarns in the shed.
Building up the harness starts by fixing it to the bottom, after which a return spring is installed which is connected to a heddle, which, in turn, is connected to the harness cord. The harness cord moves through the cumber board towards the apertured board and also through the latter to be connected to the tackle cord transferring the motion of the hooks to the harness cord.
Several harness cords may be connected to the same tackle cord (so-called “repeats”), in order that the fabric may have a repeated pattern. These several harness cords being connected to one tackle cord may be realized above the apertured board (usually with weaving machines for flat fabrics), but may also be realized between the apertured board and the cumber board (usual with pile weaving machines).
Several methods are known to build up a harness: Now in the European patent no EP 472904 granted to Schroers, a description is given how the complete chain from the bottom-connection to the harness cord is completely prepared and pre-installed, to be subsequently inserted into the harness in order to carry out the levelling (=operation to bring all heddle eyes onto the same level) while the connection of one or several harness cords to form a connecting element is realized above the apertured board, which then is connected by means of the snap-hook connection.
A drawback of the method described in EP 472904 is that during installation each harness cord has to be pulled through from the bottom upwards through two boards (cumber board and apertured board).
If this is not done in the weaving machine but in a preparatory position, then the sizeable apertured board in its entirety has to be installed in the Jacquard weaving machine. In order to improve the implementation of this process, certain elements (connecting elements or thickenings) are applied which may be used as stops. The apertured board and the cumber board are made movable by means of a drive. Such a drive will make the Jacquard weaving machine more complicated and more expensive.
In a French patent FR 2 726 011 granted to Stäubli and the American patent U.S. 68 186 128 of DTF, building up of harnesses is described, enabling the harness cords to be engaged and disengaged from the tackle cords in groups or together, for all cords in one cycle of motion.
In both cases an additional guide board is needed in order to be able to present the connecting elements in an indexed manner. As a consequence the harness or tackle cord has also to be threaded through each of those boards (cumber board, apertured board and additional guide board). Here also, the sizeable apertured board has to be installed in its entirety on the weaving machine, when threading is carried out in a preparatory position. Here also, the bottom and/or cumber board are made movable which will render the Jacquard weaving machine more complicated and more expensive. In the French patent FR 2 726 011 connecting and disengaging occurs entirely in a vertical direction (this is also the direction in which the cords, connecting elements and return springs are operating, so that it is not unlikely for an element to be disengaged while it is still operating). In the American patent U.S. Pat. No. 68,186,128, engaging and disengaging occurs in a radial direction, which, because of the motions the engaging and disengaging devices has to perform, will render the device still more complicated and more expensive. Besides complexity and manufacturing price, it is also by no means certain that the result (connecting thousands of elements in one single operation) will be indeed obtained: inaccuracies and considerable forces required to connect the whole may result in a substantial number of elements being not, or not well, connected.